Apart from four correct solutions with this arrangement of numbers in the right half of the puzzle:

x x 1 2x x 2 1x x 4 3x x 3 4

there is also this (fifth) correct solution:

3 4 1 24 2 3 12 1 4 31 3 2 4

On my system (latest Firefox version on Windows Vista SP2) all five solutions are accepted as correct when submitted.

calcpnm

Site Admin

Posted on:Wed Oct 01, 2014 9:16 am

Posts: 108Joined: Wed May 11, 2011 6:44 pm

Re: multiple solutions to 1-Oct-14, 4x4 Difficult?

Thanks for letting me know. I'm as far as having figured out that this is a bugintroduced in a more recent version of my solver

I ran an old version of the solver (from July 2010 (!)) on this puzzle, and it foundall five solutions.

Edit: found the bug, a fix for a problem which caused it to not be able to solve puzzleslarger than 15x15 (which I needed for the new book, which has one 17x17 puzzle) introduceda new bug for puzzles with cages larger than 5 cells

Challenge to you all: how to modify the current puzzle so only this solution:

Code:

3 4 1 2 4 2 3 1 2 1 4 3 1 3 2 4

is valid??

Edit #2: I changed the puzzle a bit so the above is a single valid solution.

... I'm as far as having figured out that this is a bugintroduced in a more recent version of my solver

I ran an old version of the solver (from July 2010 (!)) on this puzzle, and it foundall five solutions....

Patrick

It was one possibility among 5, but I was so unlucky that only when I entered the fifth I got the 2 points .

I was really surprised since it was the first time (IIRC) that I was seeing a violation of the "dogma" of the unicity, and thinking what would have happened in case of a 9x9, ... . I supposed most players were going to feel the same and find the solution given as correct by the program in a couple of minutes (the other four times the full grid was green but the program insisted in an "incorrect solution") and I was waiting until 24.00 CET today to talk about this bug (this time only 2 points, anyway ).